An electronic component built-in module manufactured by mounting an electronic component, such as a passive element, on a substrate is mounted on a substrate of an electronic device so as to be used. As solder used for bonding the electronic component in the electronic component built-in module and mounting the electronic component built-in module, a Pb-free solder including no Pb (lead) has been known.
When the electronic component built-in module is mounted on the substrate of the electronic device, reflow for melting the solder is performed. Various examinations have been conducted in order to prevent the solder for bonding the electronic component and the substrate in the electronic component built-in module from scattering or moving upon the reflow. For example, JP 2001-62561 A discloses a configuration in which after different kinds of metal layers to be alloyed and to be a brazing filler metal are laminated on at least one of two members to be brazed, the two members are brazed.